1. Field of the Invention
Ethylene glycol is the simplest and most important of the glycols which are widely used for many purposes and applications in industry. For example, ethylene glycol is a valuable component in antifreeze solutions for automobile engines, aircraft engines, ice-cream plants, and brewery cooling systems. Additionally, ethylene glycol finds widespread application in moistening and softening tobacco, cellophane, glue, gelatin, casein, paper and textile fibers, as well as solvents for dyes, printing inks, essential oils and various gum and resins. Similarly, ethylene glycol derivatives are important as emulsifying agents, plasticizers and explosives. Ethylene glycol was first synthesized by Wurtz in 1859, but, from a commercial standpoint, did not become important until 1925 when it was produced in large quantities via the hydration of ethylene oxide.
The ruthenium complex catalyst in combination with the ligands, as disclosed herein, exhibit superior hydrocarbon synthesis characteristics and selectivity to ethylene glycol formation when contacted with carbon monoxide and hydrogen under reaction conditions.
2. Description of the Prior Art
The reaction of carbon monoxide and hydrogen to produce monohydric and polyhydric alcohols is appreciated and disclosed by the prior art. Generally, however, most known processes produce an undesirably large mixture of alcohols, aldehydes, ethers, ketones and carboxylic acids, in addition to the polyhydric alcohol.
For example, U.S. Pat. No. 3,833,634, entitled "Manufacture of Polyfunctional Compounds", issued to Pruett et al, on Sept. 3, 1974 describes a process for the preparation of polyfunctional oxygen-containing compounds, such as ethylene glycol and its derivatives, which comprise reacting carbon monoxide with hydrogen in the presence of a rhodium complex catalyst. In particular tetrairidium dodecacarbonyl is described as unsuitable for use in the production of polyfunctional products such as ethylene glycol by the reaction between carbon monoxide and hydrogen at increased temperature and pressure.
Another process is set forth in U.S. Pat. No. 2,549,470, entitled "Synthesis of Alcohols", issued to Howk et al, on Apr. 12, 1949 discloses a catalytic process for preparing alcohols. Particularly, the reference relates to a process for synthesizing alcohols from carbon monoxide and hydrogen using a catalyst containing ruthenium. Straight chain primary alcohols and primary alcohols in which a long chain polymethylene chain is attached to a hydroxyl group having from about 3 to about 50 or more carbon atoms are prepared by contacting carbon monoxide and hydrogen with a catalyst consisting of ruthenium metal, ruthenium oxide and ruthenium carbonyl, and a hydroxylated solvent, for example, propanol, n-hexanol, etc., under reaction conditions.
U.S. Pat. No. 3,957,857, entitled "Catalytic Process for Polyhydric Alcohols and Derivatives", issued to Pruett et al, on May 18, 1976, discloses a process for making polyhydric alcohols, including ethylene glycol by reacting oxides of carbon and hydrogen in the presence of a rhodium carbonyl cluster. Particular attention should be paid to Example 9 which teaches that triruthenium dodecarbonyl did not produce polyhydric alcohols under the reaction conditions described therein.